Insulin-like growth factor-I receptor and insulin receptor association with a Src homology-2 domain-containing putative adapter.
Insulin receptor (IR) and the related insulin-like growth factor-I (IGF-I) receptor (IGF-IR) mediate a variety of metabolic and mitogenic cellular responses, some of which may involve unidentified receptor targets. A Src homology-2 (SH2) domain-coding region of a mouse protein was cloned based on its interaction with IR. It was designated mSH2-B based on its high similarity to an earlier reported rat sequence SH2-B. A role of mSH2-B in IGF-I and insulin action was suggested by the interaction of the SH2 domain with activated IGF-IR and IR catalytic fragments but not with an inactive IR catalytic fragment in the yeast two-hybrid system in vivo and by the hormone-dependent association of a glutathione S-transferase (GST) SH2 domain fusion protein of mSH2-B with both receptors in cell extracts. A comparison of IGF-IR and IR mutants lacking individual Tyr autophosphorylation sites for association with GST mSH2-B showed that homologous juxtamembrane (IR960/IGF-IR950) and C-terminal (IR1322/IGF-IR1316) receptor motifs were required. Synthetic phosphopeptides representing IR960 and IR1322 competed for GST mSH2-B binding to the receptor, suggesting that both motifs participate in the association with mSH2-B. Antibodies raised against GST mSH2-B identified a cellular protein of 92 kDa that was not found to be phosphorylated on Tyr. It co-immunoprecipitated with IGF-IR or IR, which was strictly dependent on receptor activation. IR and IGF-IR Tyr phosphorylation motifs were not identified in the complete SH2-B primary structure, suggesting that it may participate as an adapter rather than a substrate in the IGF-I and insulin signaling pathways.
Wang
J
J
Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202, USA.
Riedel
H
H
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D016466:CHO Cells; D002352:Carrier Proteins / Q000235:genetics; D002384:Catalysis; D006224:Cricetinae; D005982:Glutathione Transferase / Q000235:genetics; D047908:Intracellular Signaling Peptides and Proteins; D008024:Ligands; D051379:Mice; D008969:Molecular Sequence Data; D010748:Phosphopeptides / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D051381:Rats; D017526:Receptor, IGF Type 1 / Q000235:genetics / Q000378:metabolism*; D011972:Receptor, Insulin / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction; D018909:src Homology Domains
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008024:Ligands; D010748:Phosphopeptides; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; C492010:SH2B1 protein, rat; C115327:Sh2bpsm1 protein, mouse; D005982:Glutathione Transferase; D017526:Receptor, IGF Type 1; D011972:Receptor, Insulin